For armor penetrating kinetic energy penetrators, it is usually desirable to have as high a density as possible. For that reason, tungsten alloys are normally used having at least 90% tungsten, the balance being from the elements nickel, iron, copper, and cobalt. The densities of these alloys range from about 17.1 g/cc for a 90% tungsten alloy to about 18.7 g/cc for a 98% tungsten alloy.
However, there are certain applications in which a high density is not desirable, that is, in which a high density alloy results in a penetrator having too large a weight to function properly with the gun system being used. For those applications, it is desirable to have a series of alloys having densities below about 17.1 g/cc.
In addition, the material must also be capable of being worked so that a high hardness can be obtained which permits the penetrator to defeatthe intended targets.